Electrical signalling system with remote control



July 29, 1947 w. POULIART ELECTRIQCAL'SIGNALLING SYSTEM WITH REMOTECONTROL 2 Sheets-Sheet 1 Filed Jan. 22, 1943 I N VENTO R WIlL Y 101/6/19 ATTORNEY July' 29, 1947. w. POULlART ELECTRICAL SIGNALLINESYSTEM WITH REMOTE CONTROL Filed Jan. 22, 1943 2 Sheets-Sheet 2 N N MHaw INVENTOR mu y FOUL/HR? v N w w A Patented July 29, 1947 ELECTRICKLSIGNALLING SYSTEM WITH REMOTE CONTROL Willy Pouliart, Antwerp, Belgium,assignor to In-- ternational Standard Electric Corporation, New York, N.31., .a corporation of Delaware Application ilanuary 22, 1943, SerialNo. 473,276 ln t-he Netherlands June .23, 1941 llClaims. 1

This invention relates to new and useful :improvements in electricalsignaling systems and particularly in systems for supervising and/orcontrolling from a central :point the positions (of a plurality ofmechanisms'locatedzat one or.more distant points by-means of electricalsignals sent over a small number of wires.

Many such signaling "systems are :known in which indications are sentfrom the outlying point to the'central point, or in which .meansvareprovided for actuating mechanical or electrical devices at a distantpoint by manipulations atqthe central point. These knowneystem operateon one of the following two-principles:

(a) Code systems Each mechanism .at the distant endisprovided with oneor more contact sets, each -set corresponding to a definite position orconditionwhich itis desired to indicate. To each contact set is assigned.a predetermined code, consisting of a combination of electrical currentimpulses. These impulses may consist of the Opening-and closing of aunidirectional direct current circuit, or of trains of impulses ofpositive .or negative polarity.

The .codesending device may be directly associated with each contact setand may be-individual to each contact set, .thecode beingreleased by ..aso-called -trigger .aotion, when the contacts are actuated. Thecode-sending device may also be common to a plurality of contact sets,and the commoncodesender controlled by means individual .to each contactset.

The different codes .are received at thecentral point by an appropriatecontrolling device, which counts the number .of pulses of differentcharacteristics for thepurpose of 'identiiyingeach individual code.

Systems with individual code sending devices must, however, necessarilybe provided with..-complicated mechanisms, which .may impairthereliability of .the operation.

Systems with a common code sender must be specially designed to avoid.interfering reciprocal i action'between different indications. A.further disadvantage-is that during onerevolutionoftthe sender only onecode can besent.

(bi Synchronized stepping systems These systemsmakeuse of a rotatingmechanism, usually in the form of some type of, selector switch -with abank of terminalsand a rotating brush member at eachend of the signalingwire.

The arrangement is usually such that .each ..con- 55 or segment.

'2 tact set, the position of which has to be indicated, is connected toa definite bank terminal at thedistant point, whereas the relevantsignal isconnected'to the corresponding bank terminal at the centralpoint.

The two rotating mechanisms are arranged to rotate or step insynchronism, by means-of any one of a plurality of known methods. Duringone revolution of the :brushmember'the position of each contact set atthe distantpoint is signaled to the central point by means of a ground,the absence of ground, a;positive or negative battery, or anycombination of such indications applied to-the signaling wires.

lhe principal difliculty .in the design of such systems lies in theprovision of a temporary starting indication, which starts the rotatingmechanisms-wheneVer a contact setchange its position.

The temporary starting indication may be given :by means of anextra-spring 0r segment on the contact set, e. g., of powerstation'circuit breakers, the movable armature of the contact set makingtemporary contact with the extra spring whenever'the contact set changesits position.

Allwsuch means are, "however, of a mechanical nature and cannot be usedto signal the position-0f vmechanisms which lack said extra spring Mostof the existing systems designed :on this basis are, therefore, verylimited in their application.

The new signaling system according to this invention is of thesynchronized stepping type. The system requires two metallicsignalingwires between the distant and the central points. No earth:return connection is employed. The synchronization is achieved by verysimple means, comprising ordinary telephone relays in a straight .directcurrent circuit.

The main difference between the new signaling system and known systemsisin the method of givingthetemporarystarting indication for therotating mechanisms.

One feature of the invention provides for the giving. of this indicationin the form of a transient electrical surge in the secondary winding ofa common transformer. This makes it -;possi-b1e-to apply the newsignaling system to any type of .new :or existing signalinginstallation, even if eachcontact set comprises only two springs, i. e.,one make or one tbreak'contact, which is the smallest practicablecontact set spring combination.

.Accordingto anotherfeature of the invention a cold-cathode tube isprovided for the purpose of receiving and registering the temporarysurge indication.

In my new signaling system it is also possible to establish a telephonicconnection between the control and the distant points over the signalingwires without interfering with the signal transmission proper.

The manner in which the new signaling system functions will now bedescribed with the aid of the drawings, in which Fig. 1 is a diagram ofthe connections at the distant end, while Fig. 2 represents theconnections at the central or supervisory point, only so much beingshown as is necessary for a clear understanding of the invention.

In Fig. 1, IC designates one of a plurality of contact sets, which canbe closed or open. The contact set is shown open.

Each contact set is provided with an individual resistance 1'1. One sideof all these resistances is multipled and connected in common to theprimary winding of transformer T1; the secondary winding of thistransformer is connected to a potentiometer P, and also to the controlelectrode c2 of a cold-cathode tube L.

The cold-cathode tube is of the wellknown type, which requires aspecific control gap breakdown potential VX to light or ionize thecontrol gap between the two electrodes e1 and c2, and a much higher maingap breakdown potential Vy to light the main gap between the anode A andeither of the two electrodes e1 and e2. Once the control gap has beenionized, a potential Vz, which is considerably lower than Vy, issufficient to maintain a current in the main gap.

The control electrode 61 is permanently connected to the negative sideof battery, while the control electrode 62 (usually referred to as thecontrol anode) is connected to a biasing potential on the potentiometerin series with the secondary winding of transformer T1. The biasingpotential, which is applied in order to increase the sensitivity of thearrangement, is considerably lower than the control gap breakdown.voltage,

so that normally the tube will not be operated. An electrical surgeproduced in the secondary winding of transformer T1 will be sufficientto increase the potential difierence between c2 and e1 or between c2 andA to a value, which is equal to or higher than the control gap breakdownvoltage, or the main gap breakdown voltage.

The action of the electrical surge effect may be explained in thefollowing manner:

Let it first be assumed that the contact of a contact set 10 opens. Byremoving the ground from the corresponding resistance 71, the potentialof the common point is suddenly increased, thus causing a temporarychange of the value of the current flowing through the primary windingof T1. This change will take place in a direction indicated by an arrowdrawn in. full lines and will induce a surge in the secondary winding ofT1 in a direction such that the potential of oz will be increased withrespect to the potential 61. By a proper choice of the bias and of thedimensioning of transformer T1, this surge may be made to ionize thecontrol gap.

Let it further be assumed that thereafter the contact set closes. Byadding a resistance in the circuit the potential of the common point 0will be suddenly lowered, causing also a temporary change in the valueof the current flowing through the primary winding of T1. This changewill take place in a direction indicated by an arrow drawn in dottedlines and will induce a surge in the secondary winding of T1 in adirection such that the potential of e; will be decreased with respectto the potential of the anode A. By proper design this surge may be madesufficient tobreak down the main gap directly.

It is obvious that the number of contact sets 7 that can be connected inparallel to one trans- ,cated on a control panel.

former is limited only by practical considerations.

It is quite possible, however, to connect several transformers to onecold-cathode tube, e. g. by connecting the secondary windings in series,as indicated in dotted lines in Fig. l, where a second transformer T2 isshown.

The anode of the cold-cathode tube is connected via the winding of arelay S1 to the positive pole of the battery.

SS1 designates the power magnet of a step-bystep selector switch of thewell-known type used in telephone or similar systems. This switch isprovided with a bank of terminals, of which three levels, viz. (11, b1and 01 with corresponding brush members 021, 1 1 and 21 are indicated.It should, however, be understood that the invention is not limited tothe use of any particular type of selector switch, but that any othertypes of single or two-motion selector switches may be employed withoutchanging or modifying the principle of the invention.

Each contact set is connected also individually to an individualterminal in the selector switch bank.

The selector switch is further provided with a spark quencher Q,interrupter contact 11th and an off-normal contact ONC1. The lattercloses its lower spring set when the switch is in normal position, andopens it when the switch is in any other position.

Fig. 1 shows further a group of controlling relays, the function ofwhich will be explained later.

Key K11 simulates a contact set and is provided for test purposes.

The telephone set TA1 shown on the right-hand side of the drawing may beany type of common battery set connected to the two signaling ires wiand wz by means of two coupling condensers C12. The telephone set is fedover a retardation coil M1.

Key K12 is the telephone call key, and the purpose of it is to ring thebell at the central point as long as the key remains depressed.

In Fig. 2, SS2 designates the power magnet of a step-by-step selectorswitch of the same type as the one in Fig. 1. The switch has three banksof terminals as, b2, c2 and corresponding brush members $2, 2 and 22.The switch is provided with a' spark quencher Q2, an interrupter contact111.152 and an off-normal contact ONC2. The latter closes its top springset as long as the switch remains oiT-normal.

Each set of terminals in the banks 412 and b2 is connected to a pair ofmechanically interlocking relays IE1 and IE2. Each pair of such relayscorresponds to one contact set (IC in Fig. l). The interlocking relaysare so designed that the operation of 1R1 will cause the closure of thelefthand contact, while the operation of 1R2 will close the rightcontact. When either relay is operated and closes its contact, thecurrent may be removed from the winding of the relay without influencingthe position of the armature.

Each pair of interlocking relays is associated with a. pair ofindicating lamps IL1 and IL2, 10- These lamps are connected to give thefollowing indications. Contact IC open: lamp IL2 lights; contact closed:lamp IL1 lights.

.Fig. 2 also shows a group of controlling relays, which will be laterdescribed.

A telephone set TA2 is connected in the same manner as set TA1 in Fig.1.

Key K22 is the telephone call key, and functions in the same manner as K2 in Fig. 1.

Key CK is the central point checking key, which will also be describedlater.

Starting of indicating mechanism Let it be assumed that the signalsystem is at rest and that both selector switches are in normalposition.

Let it further be assumed that one of the indicator contacts opens. Atthat moment one resistance 11 is disconnected from ground, and this willproduce as previously explained an electrical surge in the secondarywinding of transformer T1, with the result that the breakdown voltage ofthe control gap is attained. The control gap, and subsequently also themain gap, will be ionized, and relay S1 will become energized. Relay St1operates also via the off-normal contact ONC1 and the front contact ofS1, after which relay St1 locks itself over its own front contact. Theoperation of S161 opens the anode circuit of the tube and since by thistime the effect of the surge will have disappeared, the tube will becomeextinguished.

Relay H1 will become energized in the circuit via interrupter contactInt1, brush X1 and home terminal, front contact of relay S151, toground.

When relay H1 closes its front contact, relay N1 will operate inparallel with H1. Relay N1 energizes the power magnet SS1 and operatesrelay B1 which connects battery to wire on and ground to 101 over thefront contacts of relay F1 and retardation coil D1.

Relay E1 became energized in parallel with relay St1, thereby operatingrelay F1, which reversed the battery and ground connections to thesignaling wire, for a purpose which will be explained later.

The battery connected to wire on will cause the operation of relay A22at the control station (Fig. 2) but relay A21 will not become energized,because it is shunted at that moment by rectifier R21. Relay A22 in turnoperates relay F2, which closes the energizin circuit for the powermagnet of switch SS2.

When switch SS1 (Fig. 1) attracts its armature, it opens the circuit forrelays H1 and N1. These relays are, however, made slow-releasing, sothat sufiicient time remains to check and transmit the indication in amanner to be described later.

When finally relay N1 opens its front contacts, switch SS1 will completeits first step. Relay B1 releases whereupon the relays A22 and F2 arealso released (Fig. 2). Switch SS2 will, therefore, also complete itsfirst step.

As soon as the brushes of SS1 leave their normal position, contact ONC1will open and relays ST1 and E1 release.

When the interrupter contact Int1 closes after the first step, relay H1and subsequently relay N1 will operate from the ground at the terminals(11 of SS1. The cycle of operations above described will be repeated,with the result that the two selector switches will be driven insynchronism. step-by-step, until switch SS1 comes to rest on the homeposition. terminals after one complete revolution. In this position theground connection to relay H1 is removed and both switches, therefore,stop rotating.

Let it now be assumed that one of the indicator contacts closes. In thiscase, as has already been explained above, the electrical surge in thesecondary winding of T1 will cause the breakdown of the main gap of thetube, after which the opcl'ation of the circuit continues as above desribed.

Transmission of contact set positions Every time switch SS1 stops on aset of bank terminals, to which an indication contact set is connected,a check is made over level In to determine, whether the contact set isopen or closed. If the contact is closed, there will be a ground on theb1 level terminal, and if the contact is open, there will be no suchground.

If a ground is present, relay E1 will operate over .the brush y1,causing in turn the operation of relay F1, which will connect battery toWire 1112 and ground to 201.

If there is no ground, the relays E1 and F1 will not energize, so thatbattery is connected to wire 101 and ground to wire 1.02.

In the control station the corresponding check for battery and ground isperformed by relays A21 and A 2, which are shunted by two rectifiers R21and R22 in such a way that A22 operates only with battery on wire 102while relay A21 operates only with battery on Wire 1111. The relays A21and A22 energize locally relays E2 and F2, respectively, and either oneof these relays advances the brushes of switch SS2 in synchronism withthose of SS1, once the home position has been left.

The arrangement is such that the first starting pulse is always given inthe form of a battery on wire m2, which causes the relays A22 and F2 tooperate. As soon as the brushes of SS2 leave the home position, relay G2operates, after which the left front contacts of relays E2 and F2 areconnected in parallel, until the brushes have completed theirrevolution.

Depending whether relay E2 or relay F2 has been operated, a ground isconnected to relays IE2 or IE1 via brushes $2 or 1 2. This groundenergizes temporarily one of the indicating relays, which locksmechanically and lights the corresponding indicating lamp.

The following table gives the relationship between the contact setposition and the operation of the various apparatus involved. A signindicates that a relay is energized, or a lamp lit, while a signindicates that a relay is deenergized or a lamp extinguished.

1 Ground. 2 Battery.

Remote control from central point In any remote signaling system it mustbe possible for the central p int supervisor to check at any moment thecorrectness of his lamp indications. For this purpose it is necessaryand sufiicient to provide the supervisor with means to start theselector switch at the distant point by a simple manoeuver at thecentral point.

According to the invention this verification is performed as follows:

As soon as the supervisor depresses the check key CK in Fig. 2, relaysD2 and B2 energize and connect battery to Wire 1121 and ground to wire102. This causes the operation at the distant point of relay A11, whilerelay A12 cannot operate clue to the shunting effect of rectifier R12.Relay A11 in turn operates relay G1.

When the supervisor releases key CK, relays D2, B2, A11 and G1 arede-energized, but relay G1 releases more slowly than relay A11, so thatthe ground at the back contact of relay A11 will be on long enough toenergize relay Sti, which locks. Relay E1 energizes in parallel withS751.

The operation of relay St1 starts the advancement of the selectorswitches as explained above, and during the full revolution of thebrushes the positions of all the contact sets are checked.

As soon as switch SS2 leaves the normal position, the check lamp CLlights as an indication that the starting operation has been successful.

In the preceding description the relays A11, A12, A21 and A22 weredescribed as functioning on an electrical current of a predetermineddirection by means of a properly poled rectifier or other nonlinearresistance connected in parallel to each relay. It is evident that thesame result could be obtained by using ordinary polarized relays of anysuitable design, the relays A11 and A12 and A21 and A22, respectively,being polarized in opposite directions.

Telephone call If a person at the distant point desires to establish atelephone communication with the central point, he removes the receiverand temporarily depresses the telephone call button K12, therebyoperating relay B1. This relay connects battery to wire on and ground towire 202, resulting in the operation of relay A21 at the central point.The latter in turn operates relay E2, which closes the circuit for adirect current bell, a regular telephone drop or any other suitablesignaling device. The bell will ring, as long as key K12 remainsdepressed.

The supervisor removes the receiver, whereupon the conversation may takeplace. 'If the supervisor at the control station desires to call thedistant point, he removes the receiver and depresses the telephone callkey K22, thereby operating relay B2, This relay connects battery to wire202 and ground to wire w1, resulting in the operation of relay A12 atthe distant point. The latter closes the circuit for a bell, a drop orany other suitable signaling device. The bell will ring as long as keyK22 remains depressed.

When the person at the distant point removes the receiver, conversationmay take place.

It is obvious that the telephone conversation once established, iscarried on without interfering with the signaling.

The supervisor at the control station should, however, not originate atelephone call while the check lamp is burning, because that mightinfluence the correct receipt of the signals.

The person at the distant end can only originate a call, while switchSS1 is in normal posi tion. If key K12 is depressed, while the brushesof the switch are rotating, this has no effect.

8 Testing facility The person at the distant end can verify that theequipment starts out correctly by depressing the test key K11. B doingso he connects a resistance m in parallel to the resistance T1 and thishas the same effect as if the contact set had been closed.

Alarms .TE, but this relay has not sufiicient time to leave its backcontact during one revolution of SS2.

If, however, for some reason the brushes of SS2 are prevented fromreturning to normal within a predetermined lapse of time, thethermostatic relay will function, resulting in the operation of thealarm relay N2 via front contacts of the relays H2, TE and G2. Relay N2locks to a back contact of key CK and closes the contacts for actuatingan appropriate alarm signal. Relay N2 also closes the local circuit forthe restoration of switch SS2 via its own interrupter and the offnormalcontact ONC2. The brushes of the switch, therefore, return to normal andthe switch cannot again be taken into use, before the supervisor hasdepressed key CK.

What is claimed is:

1. In an electrical signaling system, a variably operable first andsecond switch, two metallic wires between said switches, indicatingmeans associated with the first switch, a plurality of mechanisms and acorresponding plurality of contact sets associated with the secondswitch, said mechanisms having a plurality of positions, cooperatingcontacts for each switch, a resistance for each contact set, acold-cathode tube, means responsive to a change in the position of anyof said contact sets to produce an electrical surge to ionize thecold-cathode tube, means for operating the second switch controlled bythe tube, means for operating the first switch controlled by the secondswitch, and an actuating circuit for said indicating means controlled bysaid contact sets over said wires and the cooperating contacts of saidswitches.

2. An electrical signaling system according to claim 1, characterized inthat one end of each resistance is connected to its associated contactsset, and a multiple connection from the other end of all saidresistances to the primary winding of said transformer.

3. An electrical signaling system according to claim 1, a source ofpotential, means for applying a predetermined biasing potential to thecontrol electrode of the cold-cathode tube in series with the secondarywinding of said transformer, the biasing potential being lower than thevalue of the control gap breakdown voltage of the tube.

4. In an electrical signaling system, a central and a distant point, twometallic wires between said points, indicating means at the centralpoint, a plurality of variably operable contact sets at the distantpoint, a switch at the central point having cooperating contacts, aswitch at the distant point having cooperating contacts, a resistancefor each contact set at the distant point, a

cold-cathode tube at the distant point, means responsive to a change inthe position of any contact set to produce an electrical surge to ionizethe cold-cathode tube, means for starting the switch at the distantpoint controlled by the tube, means for starting the second switch atthe central point controlled by the first switch, and an actuatingcircuit for the indicating means controlled by said contact sets oversaid wires and cooperating contacts of said. switches.

5. The electrical signaling system according to claim 4 and in which thetube has an anode, two control electrodes, a main gap and a control gap,a source of biasing potential for one of said control electrodes, andmeans including a circuit operable when a contact set closes to producean electrical surge of such a magnitude and direction as to cause thebreakdown of the tube main gap, and to produce, when a contact setopens, a surge of such a magnitude and direction that it will, aided bythe biasing potential, cause the breakdown of the tube control gap.

6. In an electrical signaling system, a central and a distant point, twometallic wires between said points, indicating means at the centralpoint, a plurality of variably operable contact sets and a resistanceconnected with each set at the distant point, a switch at each of saidpoints having cooperating brushes and terminals, automatic means foreach switch to operate its brushes successively to engage all of itsterminals, a transformer having primary and secondary windings, and acold-cathode tube at the distant point, a path closed by any contact setincluding the resistance associated therewith to produce in thesecondary winding of the transformer an electrical surge, a connectionfrom said secondary winding to the cold-cathode tube to ionize it bysaid surge, means for starting the automatic opera tion of the switch atthe distant point controlled by the tube, means for starting theautomatic operation of the switch at the central point controlled by theother switch, and an actuating circuit for the indicating meanscontrolled by the contact sets over said wires and the brushes anterminals of the two switches.

7. In an electrical signaling system, a central and a distant point, twometallic wires between said points, indicating means at the centralpoint, a plurality of variably operable contact sets located at thedistant point, a variably operable switch at the central point, a firstrelay responsive to positive and a second relay responsive to negativeimpulses connected at the central point with said wires, a variablyoperable switch at the distant point, other relays at the distant pointfor applying positive or negative pulses to each wire in a closedcircuit, a cold-cathode tube at the distant point, means responsive to achange in the position of any contact set to produce an electrical surgeto operate the cold-cathode tube, means responsive to the operation ornon-operation of said tube variably to operate said other relays, meansfor operating the switch at the distant point controlled by the tube,means responsive to the operation of either the first or the secondrelay for causing the switch at the central point to perform oneoperation.

8. The signaling system according to claim '7, and circuits for saidindicating means controlled by said first and second relays.

9. The system according to claim 7 and in which each switch has a bankof terminals and a brush cooperating therewith, a connection from eachcontact set to a different terminal in the bank of the switch at thedistant point, and circuits for the other relays controlled over thelast mentioned contact bank for determining whether a positive ornegative pulse will be applied to a wire.

10. The system according to claim 7, and a pair of mechanicallyinterlocking relays at the central point, and circuits therefore jointlycontrolled by the first and second relays so that the receipt of a pulseof one polarity will cause the operation and blocking of the firstinterlocking relay, while the receipt of a pulse of the oppositepolarity will cause the operation of the second interlocking relay andthe de-blocking of the first interlocking relay.

11. The system according to claim 1, a special signal at the centralpoint, a circuit for said special signal controlled by the first and thesecond relays, and a calling button at the distant point for controllingsaid first and second relays.

WILLY POULIART.

